Is it permissible to pray Istikhara concerning a matter over which there is a difference of opinion between permissibility and prohibition?

The position of the layman regarding matters of difference is to ask reliable scholars. If the fatwas contradict each other, then he may choose the more cautious, the easier, or be given a choice. If the ambiguity persists after asking the scholars, there is no objection to performing Istikhara (prayer for guidance), because it is for matters where the correct course of action is unknown. Indeed, Umar ibn al-Khattab (may Allah be pleased with him) performed Istikhara regarding a jurisprudential matter that was unclear to him. A student of knowledge, however, should strive to ascertain the correct view and perform Istikhara.